The Bacillus subtilis Response Regulator Gene degU Is Positively Regulated by CcpA and by Catabolite-Repressed Synthesis of ClpC

Abstract

In Bacillus subtilis, the response regulator DegU and its cognate kinase, DegS, constitute a two-component system that regulates many cellular processes, including exoprotease production and genetic competence. Phosphorylated DegU (DegU-P) activates its own promoter and is degraded by the ClpCP protease. We observed induction of degU by glucose in sporulation medium. This was abolished in two mutants: the ccpA (catabolite control protein A) and clpC disruptants. Transcription of the promoter of the operon containing clpC (PclpC) decreased in the presence of glucose, and the disruption of ccpA resulted in derepression of PclpC. However, this was not directly mediated by CcpA, because we failed to detect binding of CcpA to PclpC. Glucose decreased the expression of clpC, leading to low cellular concentrations of the ClpCP protease. Thus, degU is induced through activation of autoregulation by a decrease in ClpCP-dependent proteolysis of DegU-P. An electrophoretic mobility shift assay showed that CcpA bound directly to the degU upstream region, indicating that CcpA activates degU through binding. The bound region was narrowed down to 27 bases, which contained a cre (catabolite-responsive element) sequence with a low match to the cre consensus sequence. In a footprint analysis, CcpA specifically protected a region containing the cre sequence from DNase I digestion. The induction of degU by glucose showed complex regulation of the degU gene.

YvoA and CcpA Repress the Expression of chiB in Bacillus thuringiensis

“…We then tried to determine whether Hpr or Hpr-Ser 45 -P could further stimulate CcpA Bt binding to cre chiB . Hpr and HprSer 45 -P (2 M each) were mixed in the mixture for the reaction of CcpA Bt with Pcre. We found that Hpr did not increase the affinity of CcpA Bt for the DNA fragments (Fig.…”

Bacterial Competition Reveals Differential Regulation of the pks Genes by Bacillus subtilis

“…In addition, secondary control mechanisms may finetune expression in response to external and internal conditions or signals through DegU, ComA, and ScoC. For example, DegU is induced by the presence of glucose through catabolite regulator function (63). Thus, a DegU-dependent timing mechanism may exist for initial repression by dephospho-DegU, followed by activation through DegU phosphorylation and inhibition of motility (64).…”

Regulation of the Response Regulator Gene degU through the Binding of SinR/SlrR and Exclusion of SinR/SlrR by DegU in Bacillus subtilis

“…The P2 promoter, which is located upstream of the degU P3 promoter, has been known to be activated only by the transcription factor TnrA either under nitrogen starvation conditions or in a disruptant of glnA encoding glutamine synthetase (2,43). The putative TnrA-binding site, the region from nucleotides Ϫ145 to Ϫ129 relative to the transcription start site of P3, is overlapped by the catabolite control protein A (CcpA)-binding sequence (44). In the presence of glucose, the degU P3 promoter is positively controlled by CcpA.…”